Vertcoin (VTC) has fallen prey to a 51% attack, with some estimates suggesting losses have already surpassed $100,000 as a result of double spend transactions on the chain. It is the latest example of a 51% attack, where attackers take control of a majority share of a network, reflecting the inherent weaknesses in the proof of work model.

According to a Medium post by Mark Nesbitt, a security engineer at Coinbase who identified the attack, the requirement for ‘honesty’ in proof of work remains the key vulnerability to attacks of this kind. He wrote: “The “honesty” of more than half of miners is a core requirement for the security of [BTC] and any proof of work cryptocurrencies based on [BTC]. Honest action, in this context, means following the behavior described in the…white paper. This is sometimes described as a “security risk” or “attack vector,” but is more accurately described as a known limitation to the proof of work model.”

“Failure to meet this requirement breaks several core guarantees of the Bitcoin protocol, including the irreversibility of transactions,” according to Nesbitt.

The attack follows on from several other similar attacks this year, including those affecting MONA, BTG and XVG. According to Nesbitt, this demonstrates the vulnerability of the so-called ‘long tail’ of crypto assets, as well as the weaknesses of the proof of work system.

“These attacks on VTC are not the only examples of a successful 51% double spending attack. 51% attacks occurred in BTG, XVG, and MONA earlier this year; this is merely another incident that shows that threat actors exist that are both resourced and sophisticated enough to execute this kind of attack. This recent spate of successful 51% attacks has significant implications on what is often referred to as the “long tail” of cryptocurrency assets,” he explained.

“There are a large number of cryptocurrencies, including many based on [BTC], that implement their own proof of work based blockchains. Observers of the industry have claimed that these assets have the same properties as SegWit. This claim has now been undeniably, empirically proven to be false.”

With attacks of this kind becoming increasingly common, it looks as though more unsuspecting crypto investors will be caught out by investing in insecure tokens.